Sealant fluids, more specifically barrier fluids and buffer fluids are the external fluids that are used in wet seals to prevent leakage of process fluids to the environment. They are used in devices such as pumps, compressors, and other types of turbomachinery in which the pressure of the process fluid is increased. A barrier fluid may also be used as a buffer fluid. A barrier fluid may be maintained at a pressure that is higher than that of the process fluid, while a buffer fluid is maintained at a pressure that is the same as or lower than that of the process fluid. The pressure employed is dependent upon the types of seals used in the machinery.
There are several purposes for using a sealant fluid, including:
(a) insulating a hazardous process fluid which should not be released to the environment;
(b) minimizing pollution problems;
(c) minimizing leaks and waste of an expensive product; and
(d) minimizing unscheduled down time.
A sealant fluid should be:
(a) compatible with the process being performed by the machinery;
(b) compatible with the seal materials;
(c) a good lubricant and heat transfer medium for the seal faces; and
(d) benign to the environment and to workers.
Sealant fluids are generally selected from the group comprising mineral oils, polyalpha olefins (PAO's), kerosene or diesel, glycols, alcohols and water. PAO based sealant fluids provide excellent performance over mineral oil diesels in terms of oxidative stability, high temperature performance and low temperature performance PAO based fluid is expensive, however. GTL based formulations have been developed that provide excellent performance at reduced costs. The GTL and CTL based formulations possess high viscosity index and low pour point, and are made using high quality base oil (see Table 1) that will soon become readily available at prices competitive to conventional Group II and Group III base oils.